If the point of contact on the wall is ruled 'inbounds', then I suppose that a legal stance would be one where your feet are both 100% inbounds (not over the edge of the wall at all) on top of that wall.. that doesn't look like a fun putt, to me. :P

I think you're correct.

...and yes, that putt sucked. Fortunatly, I have some really long legs, but it was still quite a stretch.